CVE-2026-68173

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description An issue exists in the ublk component where the system waits on ub->completion instead of ublk dev ready(). Because ub->completion is only re-armed by a successful START USER RECOVERY, a ublk server sending END USER RECOVERY without a successful start can cause the system to rely on a stale completion from a previous recovery cycle. This leads to the device being marked as LIVE and the requeue list being kicked while the FETCH stream is still running and ubq->canceling is set. Consequently, requests may be stranded via ublk abort rq() in the ublk queue rq common() function, potentially causing fsync operations to enter uninterruptible sleep and causing teardown to hang during tag draining. This has been observed as a lost PREFLUSH with ext4 on top of ublk following a daemon crash recovery.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.